There have been proposed various types of wireless communication systems for preventing traffic accidents by notifying a pedestrian or a driver of another vehicle of the existence of a host vehicle (i.e., calling attention) through direct wireless communication (i.e., wireless communication not via a telephone network) between an in-vehicle device installed in the vehicle (host vehicle) and a mobile terminal device provided on the object (e.g., a pedestrian or a another vehicle) (see Patent References 1 and 2, for example).
The Patent Reference 1 describes a wireless communication system in which an in-vehicle wireless communication device (in-vehicle device) installed in a vehicle and a pedestrian mobile wireless communication device (mobile terminal device) carried by a pedestrian perform direct wireless communication. In this system, the in-vehicle device transmits a pedestrian transmission signal including identification information (ID) on the mobile terminal device to the mobile terminal device. The mobile terminal device judges whether or not identification information on the mobile terminal device itself is included in the received pedestrian transmission signal, and calls attention of the pedestrian if the identification information on the mobile terminal device itself is not included in the received pedestrian transmission signal.
The Patent Reference 2 describes a traffic information communication system in which an in-vehicle communication device (in-vehicle device) installed in a vehicle and a cellular phone device (mobile terminal device) carried by a pedestrian perform wireless communication. In this system, the in-vehicle device identifies a mobile terminal device as the target of the attention by using an identifier (ID) acquired from the mobile terminal device and transmits information including the ID of the mobile terminal device. The mobile terminal device receiving the information outputs an attention display on an output unit of the mobile terminal device if the ID included in the received information coincides with the ID of the mobile terminal device (host terminal).